Project Summary: Environmental and occupational exposures to manufactured nanomaterials have markedly increased during the past recent years, and in all likelihood this trend will continue as new nanomaterials are being increasingly produced and used by various industries. This trend has been of great concern as the adverse health effects of nanomaterials are relatively unknown and understudied. Recent studies have shown that pulmonary exposure to carbon nanotubes (CNT), one of the most widely used nanomaterials in industry, results in rapid and progressive interstitial lung fibrosis in animals without causing persistent lung inflammation, which is normally associated with other known fibrogenic agents. This unusual fibrogenic effect of CNT raises important health issues since the exposure could result in deadly and incurable lung fibrosis. We hypothesize that CNT, due to their unique properties such as exceptionally small size, large aspect ratio, and chemical composition can rapidly enter the lung, penetrate the alveolar epithelial barrier, and interact with specific lung cells such as interstitial lung fibroblasts to induce fibroproliferation and extracellular matrix accumulation, which are characteristics of lung fibrosis. We also propose that such induction is mediated by signaling cascades that involve phosphatidylinositol-3-kinase(PI3K)/Akt activation and redox regulation of the profibrogenic and angiogenic factors such as TGF-b and VEGF. In Aim 1, we will determine the impact of certain nanoparticle characteristics (e.g., diameter, aspect ratio, dispersion status, and chemistry) on CNT-induced lung fibrosis and develop rapid in vitro screening assays which may be predictive of the in vivo fibrogenic response. Aim 2 will delineate key signaling pathways and fibrogenic factors involved in the induction of fibrosis by CNT in order to identify potential biomarkers and drug targets for diagnosis and treatment of the disease. Aim 3 will investigate the involvement of angiogenesis and angiogenic factors in the development of pulmonary fibrosis induced by CNT. Aim 4 will determine redox regulation of CNT-induced fibrogenesis and angiogenesis and elucidate the underlying mechanisms. Through this application, we expect to define key nanoparticle characteristics and a set of in vitro screening assays for evaluation of the potential fibrogenicity of nanoparticles in vivo. Such information will be important for safe use of nanotechnology. The proposed studies will also identify molecular targets for early detection and treatment of fibrotic lung diseases caused by nanomaterials.